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JAMB Chemistry 1982 Question 22

Question 22

Mole Concept and Stoichiometry

1.00 g of a mixture of calcium carbonate and calcium oxide liberated 0.33 g of carbondioxide on strong heating. The percentage of calcium oxide in the mixture is (Ca = 40, C = 12, O = 16)

  1. A.5
  2. B.15
  3. C.25
  4. D.35
  5. E.50
Show the answer and explanation

Answer: C (25)

Explanation

100 g CaCO3 gives 44 g CO2, so 0.33 g CO2 came from 0.75 g CaCO3. The rest, 0.25 g, is CaO: 25%.